Lamps with lamp sockets on both sides, in particular fluorescent lamps are well-known in the art. Reference is made for example to DE 10 2007 054 930 A1 co-owned by applicant. Fluorescent tubes of this type with sockets on both sides include socket contacts configured as contact pins at their respective ends, wherein the socket contacts are respectively inserted into a lamp holder. These are typically sockets with a rotor in which the contact pins are provided to the rotor through a slot in the holder housing and are moved into a contact position through subsequent rotation of the lamp while moving the rotor along in which contact position the socket contacts become electrically connected with the contact pins of the lamp and a mechanical support of the lamp is also provided. Lamps of this type are used in light fixtures which implement elongated light bands in offices and industrial buildings, warehouses and even in private homes. Fluorescent lamps with sockets on both sides have become popular in many areas due to their lighting options and also because they have a higher light output at identical electric power compared to other conventional illuminants.
Fluorescent lamps with sockets on both sides, however, have a few disadvantages when inserting and dismounting the lamp since the socket contact pins of both lamp ends are typically not synchronously insertable into the holders, which is on the one hand side due to user handling and caused by the fact that inserting the socket contact pins into the tight insertion openings of the holders is imprecise. The longer the fluorescent lamp is itself, the more uncomfortable it is to handle. Due to low intrinsic stability of the fluorescent lamps a user has to be very careful not to destroy the lamp during insertion or through unintentional dropping.
Furthermore, rather elongated fluorescent lamps with sockets on one side are known in the art which are inserted into light fixtures having only one lamp holder. In order to reduce mechanical loading of the holder and to provide correct orientation of the lamp in the light fixture, the lamps can be provided with an additional support for the fluorescent lamp, wherein the additional support typically is an interlocking element. The interlocking element partially envelops the fluorescent lamp which does not have any additional support device itself. Thus, reference is made to articles 26.746.1001 and 26.726-013 in the catalogue 2008-2011 on pages [03] 52 through [02] 54 of the applicant. In systems of this type mounting the fluorescent lamp can be easily performed through lateral insertion. Typically significant forces have to be applied for inserting the lamp into the holder. However, since the holder for the lamp socket includes a mounting movement end stop, a user has the additional safety of not losing the lamp out of his hand unintentionally. The same applies for interlocking the lamp in the support element at the light fixture. Also here, the support element includes a mounting end stop for the fixation movement.
Dismounting a fluorescent lamp of this type is much more inconvenient for the user since the sensitive fluorescent lamp has to be pulled out of the interlocking support element of the light fixture with comparatively high force and has to be pulled out of the lamp holder thereafter. The typically sudden overcoming of the support forces of the support element and of the holder causes a sudden movement of the lamp in dismounting direction which induces the risk that the lamp is accidentally dropped or that the lamp impacts the light fixture housing.
Old lamp shapes have an additional disadvantage in that a concatenation of plural lamps does not produce light in sections that are covered by the lamp sockets and the lamp holders. This generates shaded portions in light bands that are formed from plural lamps.
Last not least LED lamps are known in the art as replacement for fluorescent lamps. These LED lamps, however, use the known socket and holder systems. In order to be used as retrofit and replacement lamps for existing light fixtures such LED lamps emulate the classic configurations of fluorescent lamps.
In particular, LED lamps configured as classic fluorescent tubes typically include an aluminum body for cooling the LEDs, which aluminum body extends over an entire length of the lamp. Compared to the glass tube of a fluorescent lamp there are significant lengths expansions caused by operational heating which can cause tensions in the installed lamp or even a deformation of the entire light fixture. Additionally, there are contact problems when the socket contacts disengage from the holder contacts due to length reduction during cooling of the lamp.